[gmx-users] ewald_rtol

[Andrew DeYoung]

Hi,

Does the parameter ewald_rtol affect PME electrostatics (coulombtype = PME),
or does ewald_rtol only affect Ewald electrostatics (coulombtype = Ewald)?
In the manual description of the .mdp parameters
(http://manual.gromacs.org/current/online/mdp_opt.html#el), it says in the
Ewald section, "The relative accuracy of direct/reciprocal space is
controlled by ewald_rtol."  Similarly, page 100 of the manual says, "The
ewald_rtol parameter is the relative strength of the electrostatic
interaction at the cut-off. Decreasing this gives you a more accurate direct
sum, but a less accurate reciprocal sum."

However, I do not see ewald_rtol specifically discussed in any of the manual
sections on PME.  Does this mean that ewald_rtol is only relevant for the
(normal, classical) Ewald sum electrostatics?

Thank you!

Andrew DeYoung
Carnegie Mellon University